Developing Agent Plugin for Github Copilot (VSCode and CLI)

Hi all,

We're rolling out skills, agents, and MCP servers across our organization using the plugin format, but on GitHub Copilot (CLI and VSCode), not Claude Code. We've hit a wall on one thing: injecting credentials for different MCP server configurations .

We tried using ${input:...} and ${user_config...} with the corresponding entries in plugin.json, but neither approach worked for us.

Right now our workaround is to use environment variables plus a how-to guide for setup, but we'd much prefer a built-in solution if one exists.

Has anyone gotten variable substitution (or any other native mechanism) working for MCP credentials in a plugin manifest under Copilot? Any pointers, working examples, or docs we might have missed would be hugely appreciated.

Thanks!